This invention is directed to a milk protein hydrolysate composition, and processes for preparing the same which utilize a specific enzymatic treatment of casein in the presence of alkali. More specifically the invention is directed to the use of specific fungal protease enzymes for treating casein at alkaline pHs.
In my U.S. Pat. No. 4,363,820, the entire contents which are herein incorporated by reference, I disclose a composition based on casein and a process for preparing that composition. That composition is extremely useful in preparing canned tuna and other seafood flesh products. The composition is prepared by treating casein with a very basic solution of sodium or potassium hydroxide to partially hydrolyze it.
The composition of U.S. Pat. No. 4,363,820, is directed to uses as an additive to solid food products of animal origin. It is not primarily directed toward utilization in beverages. For utilization in beverages, animal-derived protein products and/or compositions must have certain essential flavor characteristics.
Milk is a well known and widely utilized foodstuff. Bovine milk constitutes a major industry in many countries of the world. The milk obtained from the cow contains proteins, carbohydrates, and lipids as well as vitamins, minerals, and the like. The protein content of milk is an extremely useful entity by itself when freed from other milk components such as the carbohydrates and lipids. Casein, the major milk protein, is normally separated from the whey by precipitating the casein at a pH below its isoelectric point. Normally, in situ bacterial lactic acid precipitation is utilized.
The acid precipitated casein is composed of several related fractions. These combined fractions are very cationic in nature and somewhat hydroscopic. Unless subjected to extreme drying conditions, the casein so obtained will retain a small fraction of water of about 9 and 10%.
Casein has been isolated and utilized for many years. It was recognized several decades ago that casein could be utilized as an additive to other foodstuffs in addition to its use as a primary foodstuff. Because casein is primarily composed of proteins, the useful properties of these proteins have been sought when utilizing casein as an additive.
U.S. Pat. No. 2,547,136 patented in 1951, describes utilizing an enzymatically treated casein as a food additive for imparting useful whipping properties similar to those obtained from eggwhites. This patent describes treating casein with a variety of proteolytic enzymes including trypsin, erepsin, pepsin, papain, and ficin. The patent notes that trypsin was found to be the most satisfactory for the purposes of the invention. As described in this patent, the casein is treated with trypsin at an elevated temperature of 50.degree. C. After the enzymatic treatment, the reaction solution was acidified and filtered to remove undesirable products. After concentration by evaporation, and again filtering the solution, the product was isolated by raising the pH to about pH 7.5 and spray drying.
Approximately one decade after issuance of U.S. Pat. No. 2,547,136, U.S. Pat. No. 3,036,918 was issued. This patent noted that previously known caseins were undesirable because of the development upon storage or shelving of certain undesirable flavor characteristics. In order to overcome the deficiences of the prior known treated caseins, U.S. Pat. No. 3,036,918 taught the inclusion of an oxidation process after enzymatic treatment. The inventors of U.S. Pat. No. 3,036,918 also noted that extensive protein hydrolysis of casein also resulted in off flavor characteristics associated with the products thereof. In view of this, in addition to the oxidation step, U.S. Pat. No. 3,036,918 also teaches titration of the amino acid tyrosine in order to prevent over excessive protein hydrolysis.
U.S. Pat. No. 3,036,918 teaches that the ascorbic acid fraction of casein, which prior to the issuance of this patent had been accepted as a preservative for such products, in fact, led to undesirable flavor characteristics. In order to circumvent these undesirable flavor characteristics, U.S. Pat. No. 3,036,918 teaches the above referred to oxidation of ascorbic acid after the enzymatic treatment of the casein.
Further, U.S. Pat. No. 3,036,918 teaches the equivalency of certain enzymes for enzymatic treatment of casein. Noted as useful, in U.S. Pat. No. 3,036,918, as proteolytic enzymes for treating casein are pancreatin, which is a tryspin, bromelin, a protease from pineapple Rhozyme W-15 a commercial bacterial protease, and any proteolytic fungal enzyme. Further, it also includes pepsin when utilized at low pHs, and for products wherein the flavor development would not be unobjectionable. Presumably the panacea of any objectionable flavor characteristics derived from casein treated with the above referred to enzymes, would be the oxidation which follows the enzymatic treatment.
Products such as meat products and the like, have their own natural prevailing flavors which are sufficient to override and mask certain undesirable flavor characteristics of additives which might be introduced into these products. Contrary to this, beverages such as high-protein beverages and the like, do not have these natural overpowering or prevailing flavor and odor characteristics. Because of this, components which are added to high-protein drinks and the like cannot have any overriding or prevailing undesirable flavor characteristics. Heretofore, while certain casein derived proteins might have been useful for food products where there are prevailing or overriding flavor characteristics derived from the basic food product, or the casein derived proteins are utilized in such a small concentration that any undesirable flavorings are lost, casein derived proteins have not been useful in other food products such as beverages or the like which are more bland, need to be more milk-like, and do not have any "masking" agents. This is especially true in Health Food Beverages wherein artificial flavoring additives added to mask undesirable flavors would not be acceptable by the consumer.